LaF_3-KF熔盐的径向分布函数

熔盐结构具有远程无序、近程有序的特点,对其结构的表征要比完全有序的晶体和完全无序的气体困难得多.分布函数理论是迄今为止描述熔盐结构较为成熟的方法,它依据统计理论,从粒子间相互作用势能出发,去求解表征体系结构的径向分布函数.实验上获得径向分布函数主要是通过衍射法.在国内,熔盐径向分布函数的实验工作才刚刚开始.本文报导了采用X-射线衍射方法测定LaF_3-KF熔盐径向分布函数的结果.

L-B膜

L-B膜即 Langmuir-Blodgett单分子膜,它是人为地利用分子间相互作用而建立起来的特殊分子体系。在L-B膜中分子是有序的准晶体排列,其性质有别于固体和晶体,因而有人将其称为物质的第五相。用米制备L-B膜的技术称为L-B技术。

化学蚀刻法在研究共混高聚物结构中应用

共混高聚物是具有优良性能的高分子材料,近些年来这类材料的应用越来越广泛,从而对共混高聚物的研究也逐渐深入。本文将应用化学蚀刻法对丙纶高分子材料结构做以探讨。丙纶是聚丙烯(PP)与聚对苯二甲酚乙二酯(PET)经物理共混而成的,由于PET的加入可以提高丙纶染色效果,因此扩大丙纶应用范围。我们对PP与PET共混物在不同温度不用铬酸液蚀刻不同时间,通过扫描电镜观察其形态结构。实验结果表明,铬酸蚀刻液对高分子材料晶区与无定型部分可以有选择的腐蚀,使晶区与无定型区形态清晰显露,从而达到提高共混物衬差效果,对研究共混高聚物结构具有重要意义。

二(2-乙基己基)膦酸萃取Er(Ⅲ)的动力学和机理

H(DEHP)是HEH(EHP)和HDEHP的同系物,它们的结构分别为:HDEHP,(GO)_2PO(OH);HEH(EHP),(GO)(G)PO(OH);H(DEHP),(G)_2PO(OH)。其中G为2-乙基已基。 希土元素萃取分离工艺化学表明,溶剂萃取希土元素对酸度的依赖关系及相邻希土元素间的分离因素值是选择萃取剂时应优先考虑的因素。HDEHP萃取剂对中、重希士元素反萃酸度高,HEH(EHP)是一个优良萃取剂,但对Er,Tm,Yb,Lu的反萃仍需5mol/l的酸。由于H(DEHP)分子中不含酯氧原子,使得它的pK_a值比HDEHP和HEH(EHP)的高。从而,用H(DEHP)萃取希土元素时需要的水相酸度更低,反萃更容易。而且H(DEHP)

HMDSO和TFM混合气体等离子体聚合膜的结构与性能

在钟罩式内极反应器中进行了六甲基二硅氧烷(HMDSO)和四氟化碳(TFM)混合气体等离子体聚合。用IR、XPS、X射线对聚合膜结构进行了表征。等离子体共聚合膜中含有Si和F,聚合膜中元素组成依赖于起始混合气体单体的比,Si/C元素比随着混合气体中TFM浓度增加而减小,而F/C比增大。测定了复合膜的气体透过性,等离子体共聚合方法是制备气体分离膜的可行方法。同时,还测定了等离子体聚合膜的接触角,并计算了表面能。

Distribution of uranium isotopes in the main channel of Yellow river (Huanghe), China

Uranium isotopes were measured in waters and suspended particulate matters (SPM) of the main channel of Yellow River, China that were sampled during four field trips between August 2005 and July 2006. The results show that the concentration of dissolved U (2.04-7.83 mu g/l) and the activity ratio of U-234/U-238 (1.36-1.67) are much higher than the average U concentrations and activity ratios of global major rivers. Mass balance calculations using the results of simulated experiments and measurement data show that the section of the Yellow River between Lanzhou and Sanmenxia has its dissolved U derived from two sources: suspended sediments (68%) and groundwater/runoff from loess deposits (32%). Both sources are related to the heavy erosion of the Chinese Loess Plateau. (C) 2008 Elsevier Ltd. All rights reserved.

Element enrichment and U-series isotopic characteristics of the hydrothermal sulfides at Jade site in the Okinawa Trough

The geochemical and U-series isotopic characteristics of hydrothermal sulfide samples from the Jade site (127A degrees 04.5'E, 27A degrees 15'N, water depth 1300-1450 m) at Jade site in the Okinawa Trough were analyzed. In the hydrothermal sulfide samples bearing sulfate (samples HOK1 and HOK2), the LREEs are relatively enriched. All the hydrothermal sulfide samples except HOK1 belong to Zn-rich hydrothermal sulfide. In comparison with Zn-rich hydrothermal sulfides from other fields, the contents of Zn, Pb, Ag, Cd, Au and Hg are higher, the contents of Fe, Al, Cr, Co, Ni, Sr, Te, Cs, Ti and U lower, and the Pb-210 radioactivity ratios and Pb-210/Pb ratios very low. In the hydrothermal sulfide mainly composed of sphalerite, the correlations between rare elements Hf and U, and Hf and Mn as well as that between dispersive elements Ga and Zn, are strongly positive; also the contents of Au and Ag are related to Fe-sulfide, because the low temperature promotes enrichment of Au and Ag. Meanwhile, the positive correlations between Fe and Bi and between Zn and Cd are not affected by the change of mineral assemblage. Based on the Pb-210/Pb ratios of hydrothermal sulfide samples (3.99x10(-5)-5.42x10(-5)), their U isotopic composition (U-238 content 1.15-2.53 ppm, U-238 activity 1.07-1.87 dpm/g, U-234 activity 1.15-2.09 dpm/g and U-234/U-238 ratio 1.07-1.14) and their Th-232 and Th-230 contents are at base level, and the chronological age of hydrothermal sulfide at Jade site in the Okinawa Trough is between 200 and 2000 yr.

Effective AC and DC responses of nonlinear composites at higher concentration

For higher concentration of inclusions, an effective medium approximation (EMA) method is used to investigate the bulk effective response of weakly nonlinear composites, which are subject to the constitutive relation of electric displacement and electric field, D-alpha = epsilon E-alpha + chi(alpha)|E|(2) E. As an example of three dimensions, under the external AC and DC electric fields E-app = E-a (1 + sin omega t), we have derived the general effective nonlinear response of composites by the EMA method for higher concentration of spherical inclusions. Furthermore, the effective nonlinear responses at harmonics are predicted.

富营养化环境下的海洋微藻生理生化特性研究

本论文以中肋骨条藻和东海原甲藻为研究对象，研究了富营养化条件下，两种主要赤潮藻的磷酸酶活性变化、主要生化组成特征变化以及光合作用特性变化，分析了营养盐条件与微藻的主要生理生化特性之间的关系。结果表明中肋骨条藻和东海原甲藻均能诱导碱性磷酸酶和酸性磷酸酶，且两种磷酸酶具有相似的变化趋势。外界磷酸盐和胞内磷酸盐浓度越低，酶活性越高。另外两种藻均能吸收利用有机磷化合物（ATP、G-6-P和G-P），生物量明显增加。在试验初期，两种赤潮藻的单位细胞总脂和总碳水化合物含量随着营养盐的消耗而呈下降趋势，在试验后期，环境中营养盐限制时，胞内总脂和总碳水化合物含量呈上升趋势。单位细胞总蛋白含量在整个实验期间也随着营养盐的消耗呈下降趋势，但无上升现象。两种藻在低营养盐浓度处理组的单位细胞光合色素含量分别低于相对应的高营养盐浓度处理组。当P源充足时，低N处理组的藻细胞叶绿素活性较高，光合速率高于高N处理组；N源充足时，低P处理组的光合速率低于高P处理组。对两种藻的主要生理生化特性指标与营养盐浓度进行相关性分析发现，微藻的生理生化指标变化与磷酸盐浓度尤其是胞内磷酸盐浓度呈好的相关关系，而与硝酸盐浓度无显著相关性。

Behavior of uranium in the Yellow River plume (Yellow river estuary)

The Yellow River (Huanghe) is the second largest river in China and is known for its high turbidity. It also has remarkably high levels of dissolved uranium (U) concentrations (up to 38 nmol l(-1)). To examine the mixing behavior of dissolved U between river water and seawater, surface water samples were collected along a salinity gradient from the Yellow River plume during September 2004 and were measured for dissolved U concentration, U-234:U-238 activity ratio, phosphate (PO43-), and suspended particulate matter. Laboratory experiments were also conducted to simulate the mixing process in the Yellow River plume using unfiltered Yellow River water and filtered seawater. The results showed a nonconservative behavior for dissolved U at salinities < 20 with an addition of U to the plume waters estimated at about 1.4 X 10(5) mol yr(-1). A similarity between variations in dissolved U and PO43- with salinity was also found. There are two major mechanisms, desorption from suspended sediments and diffusion from interstitial waters of bottom sediments, that may cause the elevated concentrations of dissolved U and PO43- in mid-salinity waters. Mixing experiments indicate that desorption seems more responsible for the elevated dissolved U concentrations, whereas diffusion influences more the enrichment of PO43-.

Immunomodulation and antitumor activity of kappa-carrageenan oligosaccharides

The modulation of carrageenan oligosaccharides from Kappaphycus striatum on the immune system in S 180-bearing mice was investigated. The mice inoculated with S180 cell suspension were treated p.o. with carrageenan oligosaccharides (50, 100 and 200 mu g/g) for 14 days. The effects of carrageenan oligosaccharides on transplantable tumors and macrophage phagocytosis, quantitative hemolysis of sheep red blood cells (QHS),. lymphocyte proliferation, the activity of natural killer cells (NK), production of interleukin-2 (IL-2) and tumor necrosis factor-alpha (TNF-alpha) were studied. Carrageenan oligosaccharides could significantly inhibit the growth of transplantable sarcoma S180 and increase macrophage phagocytosis, the form of antibody secreted by spleen cells, spleen lymphocyte proliferation, NK cells activity, serumal IL-2 and TNF-alpha level in S 180-bearing mice. Considering all these results, it is suggested that carrageenan oligosaccharides exert their antitumor effect by promoting the immune system. (c) 2005 Elsevier Ireland Ltd. All rights reserved.

青海省不同地区羌活脂溶性化学成分的研究

采用毛细管气相-质谱法对青海省不同地区羌活脂溶性化学成分进行分析和鉴定，共分离出80余个成分，鉴定了60个，并用面积归一法确定其相对含量。结果表明，其化学成分以亚油酸、水菖蒲酮、十六烷酸及3，5-豆甾二烯为主，不同地区间羌活脂溶性化学成分种类和含量均有明显的差异。

线叶龙胆的胚胎学研究

首次报道了龙胆属华丽组的胚胎发育过程, 其代表种线叶龙胆花药四室; 药壁发育为双子叶型; 绒毡层两型起源, 细胞具双核和多核, 绒毡层细胞1- 3次分裂形成“横格”和“类胎座”, 原位退化, 属非典型的腺质型; 中层细胞两层; 药室内壁纤维状加厚。小孢子母细胞减数分裂为同时型, 四分体的排列主要为四面体形; 成熟花粉为3-细胞型。子房为2 心皮, 1室, 超侧膜胎座。胚珠10- 15列, 腹维管束彼此靠近, 并在中下部融合。薄珠心, 单珠被, 倒生胚珠。大孢子母细胞减数分裂形成的4个大孢子呈直列式排列。胚囊发育为蓼型。成熟胚囊为矩圆形。极核在受精前融合为次生核。雄蕊先熟, 异花传粉, 珠孔受精。受精作用属于有丝分裂前配子融合类型。胚乳发育为核型。胚胎发育为茄型酸浆Ⅱ变型, 当种子散落时胚只发育至球形胚阶段。结合已有的资料, 还总结了龙胆属的胚胎学特征。